Stress fractures

Report
Kevin deWeber, MD, FAAFP, FACSM
Director, Military Sports Medicine Fellowship
USUHS/Ft. Belvoir
2011
(many slides courtesy Dave Haight, MD
Outline
 Pathophysiology
 Risk Factors
 Associations
 Diagnosis
 General Treatment
 Treatment of High-Risk Cases
Stress fracture
[stress frack-chur]
 Break in a normal bone after it is
subjected to repeated tensile or
compressive stresses, none of which
would be large enough individually to
cause the bone to fail, in a person who
is not known to have an underlying
disease that would be expected to cause
abnormal bone fragility.
Insufficiency Fracture
[in-suh-fish-n-see frack-chur]
 Fracture due to repeated compressive or
tensile stresses in a bone whose mechanical
strength is reduced due to a condition that is
present either throughout the skeleton
(osteoporosis, osteomalacia, osteogenesis
imperfecta, etc.) or in a bony region (eg,
demineralization in a limb due to disuse).
Pathologic fracture
[path-o-lah-jick frack-chur]
 Fracture due to a localized loss of strength
in a bone from a disease process
immediately underlying the bone, eg, bone
tumors , bone cysts, and infections.
PREVALENCE
 1% of general population get ‘em
 1-8% of collegiate team athletes get ‘em
 Up to 31% of military recruits get ‘em
 13-52% of runners get ‘em
Most Common Sites of Stress
Fractures
 Tibia - 39.5%
 Metatarsals - 21.6%
 Fibula - 12.2%
 Navicular - 8.0%
 Femur - 6.4%
 Pelvis - 1.9%
 OTHER – 10.4%
CAUSE
 Change in load (force on the bone)
 Small number of repetitions with
large load
Large number of reps, usual load
 Intermediate combination of increased load and
repetition
PATHOPHYSIOLOGY
 Stress fracture: imbalance between bone resorption and
formation
 Wolff’s Law: change in external stress leads to change in
shape and strength of bone
 bone re-models in response to stress
 ABRUPT increase in duration, intensity, frequency without
adequate rest (re-modeling)
 Microfracture -> continued load -> stress fracture
Review of Risk Factor Types
 Intrinsic:
 Gender, genetics
 Anatomical malalignment/ biomechanical
 Dietary
 Muscle weakness/imbalance
 Extrinsic
 Training errors
 Equipment mismatch
 Technique errors
 Environmental
 Sports-imposed deficiencies
INTRINSIC RISK FACTORS
for Stress Fractures
 History of prior stress fracture
 Low level of physical fitness
 Female Gender
 Menstrual irregularity
 Diet poor in calcium and dairy
 Poor bone health
 Poor biomechanics
INTRINSIC RISK FACTORS cont
 Prior stress fracture:
 6 x risk in distance runner and military recruits
 60% of track athletes have hx of prior stress fracture
 One year recurrence: 13%
 Poor Physical Fitness – [muscles absorb impact]
 >1 cm decrease in calf girth
 Less lean mass in LE
 < 7 months prior strength tng
INTRINSIC RISK FACTORS cont
 Why female gender? [1.2-10x]
 Higher rates of other risk factors
 Poorer bone health, Menstrual irregularity, disordered
eating
 Poor bone health:
 Supplementing female military recruits with Ca and
Vit D reduced stress fracture incidence

Lappe J, Cullen D, Haynatzki G, et al.. J Bone Miner Res 2008
 FamHx osteoporosis: 3x risk
INTRINSIC RISK FACTORS cont
 BIOMECHANICAL FACTORS
 Shorter duration of foot pronation
 Sub-talar joint control
 Tibial striking torque
 Early hindfoot eversion
 Pes cavus (unproven)
 Pes planus (unproven)
EXTRINSIC FACTORS
 Increasing volume and intensity
 Footwear
 Older shoes
 Absence of shock absorbing inserts
 Running Surface?: mixed results
 Treadmill vs Track
 Activity type
ACTIVITY TYPE ASSOCIATIONS

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


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


Ballet: spine, femur, metatarsal
Runners: tibia, MT
Sprinters: navicular
Long dist runner: femoral neck, pelvis
Baseball, tennis: humerus
Gymnasts: spine, foot, pelvis
Rowers, golfers: ribs
Hurdlers: patella
Rowers, Aerobics: sacrum
Bowling: pelvis
Classic Clinical History
 Gradual onset of pain over weeks to months
 Initially pain only with activity

“can’t run through it”
 Progresses to pain after activity
 Eventually constant pain with ADLs
 Change in training regimen
 “too much too soon”
 Change in equipment
 Shoes, etc.
DIAGNOSIS: take a good History
 Sports participation
 Occupation
 Significant change in training
 Hills, surface, intensity
 Dietary History: adequacy, Vit D, Calcium
 Menstrual History
 General Health
 Past medical history
 Medications
 Family history (osteoporosis)
DIAGNOSIS: Examination
 Localized tenderness to palpation in a “High-Speed
location known to commonly sustain
Digital Imaging”
stress fractures
 Fulcrum test?
 Neither sensitive nor specific
 Hop test?
 Neither sensitive nor specific
 Risky in high risk fractures
 Tuning fork?
 43% sensitive, 49% specific
DIAGNOSIS: Biomechanical
Evaluation
 Leg length discrepancy
 70% incidence in patients w/ LE stress fractures
 Joint range of motion and ligamentous stability
 Muscle strength and flexibility
 Limb alignment (eg, genu varus or valgus)
 Foot type (eg, pes cavus or planus)
 Gait analysis in shoes worn during physical activity
 Core muscle strength (eg, abdominal, back, and hip
musculature)

IMAGING: X-ray
 Poor sensitivity
 ~ 30% positive on initial examination
 4 Possible findings
 Localized periosteal elevation
 Cortical thickening
 Focal sclerosis
 Radiolucent line
 10 - 20% never show up on plain films
Early Metatarsal Stress Fracture
One Week Later…..
Imaging: Bone Scan
 Extremely sensitive
 95% show up after 1 day
 Not very specific
 up to 24% false-positive results (stress reaction)
 Differentiate between acute and old lesions
 Acute stress fracture: all three phases positive
 Shin splint: delayed phase only
Imaging: CT scan
 Excellent fracture line detail
 More specific than bone scan
 Useful for fracture age/non-union
 Pars interarticularis, sesamoids, etc.
 DOWNSIDE: high radiation dose
Imaging: MRI
 Highly sensitive (= bone scan)
 More specific than bone scan
 still not perfect
 Cost may be lower than bone scan some places
 Non-invasive, no radiation
 Sensitive for soft tissue injury
 DOWN: less cortical bony detail than CT
Imaging: Ultrasound
 Useful if fracture superficial
 Shows hematoma, hypervascularity, periosteal
elevation, cortical defect
 Metatarsal fractures: sensitivity 83%, specificity 76%
 Balal F, Gandjbakhch F, Foltz V et al. J Rheumatol 2009
MRI vs. bone scan, CJSM 2002
 MRI less invasive, provided more information than
bone scan and recommended for initial diagnosis
and staging of stress injuries
 “Limited” MRI may be cheaper than bone scan at
some institutions
RADIATION COMPARISON
Study
mSv
relative radiation
Plain film foot
Plain film CXR
<0.01
0.02
< 1.5 days
2.4 days
Plain film pelvis
0.7
3.2 mo
Tech-99 bone scan
3 (150 CXR)
1.2 yrs
CT L-spine
CT abd / pelvis
6 (300 CXR)
10 (500 CXR)
2.3 yrs
4.5 yrs
Differential Diagnosis
 Muscle strains
 Tendinopathy
 Nerve entrapment
 Medial tibial stress syndrome
 Neoplasm
 Infection
HIGH RISK STRESS FRACTURES
 Pars interarticularis
 Femoral head
 Femoral neck
(tension side)
 Patella
 Talus
 Tarsal navicular
 Proximal fifth
metatarsal
 Great toe sesamoid
 Base of second
 Anterior cortex of tibia
metatarsal
(tension side)
 Medial malleolus
GENERAL TREATMENT for
LOW-RISK STRESS FRACTURES
 PROTECTION
 Reduce pain
 Promote healing
 Prevent further bone damage
 ACTIVITY MODIFICATION
 Rest from painful activities 6-8 weeks (or until pain-free for
two to three weeks)
 Cross-training (non-painful exercise)
 REHABILITATIVE EXERCISE
 Flexibility, strength balance
 BIOMECHANICAL CORRECTIONS
Early Treatment Speeds Recovery!
 Evaluation < 3 weeks of sx onset:
 10.4 weeks to RTP
 Evaluation > 3 weeks
 18.4 weeks to RPT
 Ohta-Fukushima M, Mutoh Y, Takasugi S, et al. J Sports
Med Phys Fitness 2002
ACTIVITY MODIFICATION
 Activity should be pain free
 Approximate desired activity
 Cycle
 Swim
 Walk
 Elliptical
 Deep water running
REHAB EXERCISE and
BIOMECHANICAL CORRECTIONS
 Muscle flexibility
 Strength training
 Excessive pronation, pes cavus, pes planus
 Limb Length Discrepancy
 Replace running shoes every…
Other Treatment Modalities
 Ultrasound: unsure
 1 study no benefit, 2 studies + benefit
 ECSWT: maybe—consider in high-risk sites
 Worked in 1 small retrospective study
 Medications:
 Iloprost: 1 small retrospective study in subchondral
stress fractures of knee
 Capicitatively Coupled Electric Fields:
 No benefit in recent RCT
HIGH RISK STRESS FRACTURES
High risk for
delayed union ,
nonunion,
refracture
 Pars interarticularis
 Femoral head
 Femoral neck
(tension side)
 Patella
 Talus
 Tarsal navicular
 Proximal fifth
metatarsal
 Great toe sesamoid
 Base of second
 Anterior cortex of tibia
metatarsal
(tension side)
 Medial malleolus
High-Risk Tibial Stress Fracture
 Anterior, middle-third stress fractures are
very concerning
 Tension side of bone
 May present like shin splints
 Seen more commonly in jumpers and leapers
 If you see “dreaded black line” on x-ray, poor
prognosis
Management of High-Risk Tibial Stress Fx
 4-6 months of rest +/immobilization
 ? Therapeutic US or SWT
 Surgery if not healing in 4-6 months
 Intramedullary rod
Proximal 5th
metatarsal
stress fracture
Mgmt. of 5th Metatarsal Stress Fracture
 Sxs <3 wks, neg x-rays:
 Avoid WB activity; 5th MT unloader orthotic
 Sxs > 3 wks or + x-rays
 Cast, NWB x 6 wks OR
 Screw fixation (faster RTP)
 Non-union: Screw-it!
Lumbar Spondylolysis
 Stress fracture of the pars interarticularis
 Caused by repetitive hyper-extension
 Often develops in the teenage or pre-teen years
 May be bilateral
Sports Associated with Spondy
 Football (offensive lineman)
 Gymnastics
 Wrestling
 Diving
 Tennis
 Volleyball
Physical Exam- Spondy
 Tenderness to palpation over spines > paraspinal
muscles
 Extension exacerbates pain
“Stork test”—not very sensitive
 Tight hamstrings- cause or effect?
Imaging Suspected Spondy
 AP & lateral x-rays
 r/o other bony causes
 Obliques don’t change management
 Also order SPECT bone scan
 MRI not as sensitive
 CT with fine cuts: prognostic
 Acute vs sclerotic
Treatment- Spondy
 Relative rest from painful activity
 Physical Therapy referral
 Williams flexion-based exercises:
 Spine Surgeon referral
 Anti-lordotic bracing
 Brace 6 weeks - 6 months (controversial)
 Return to activity in brace when pain-free
 Surgery if fail treatment
Femoral Neck Stress Fracture
 Vague anterior or medial groin/hip pain
 Early diagnosis critical
 Anterior hip tenderness
 Log-roll pain
 Pain with straight-leg-raise
 If x-rays negative, order MRI
 Crutches/NWB until ruled out!
 MRI diagnostic imaging of choice for femoral neck
stress fractures
Femoral Neck Palpation
Iliopsoas bursa
Femoral Neck
Stress Fractures
 Compression side.
 Inferior part of femoral neck
 Less likely to become displaced
 Complications possible
 Treatment:
 Fatigue line <50% neck width:
Crutches/NWB until asymptomatic,
then relative rest 4-6 wks
 Fatigue line >50% neck width:
surgical fixation
Femoral Neck Stress Fx
 Tension side: HIGH-RISK
 Superior cortex or
tension side of neck
 High propensity to become displaced
 Frequent complications
 Treated acutely with internal fixation
Tarsal Navicular Stress Fx:
HIGH-RISK
 Consider in: Sprinters, Jumpers, Hurdlers,
Basketball, Football
 Mean interval of 7 -12 months before diagnosis
 “DON’T BE THAT GUY” WHO MISSES
 Vague mid-foot medial arch pain
 Foot cramping
IT
Tarsal Navicular Stress Fx
 X-rays usually negative
 MRI or thin-cut CT better than bone scan
Tarsal Navicular Stress Fracture
 Meta-analysis 2010:
 NWB cast better than WB


6-8 weeks
Semirigid orthotic during subsequent ambulation
 NWB trend better than surgery

Torg JS, Moyer J, Gaughan JP, Boden BP. Am J Sports Med
2010.
 Nonunion/displacement: surgery
Navicular Stress Fx Return to Play
 After casting, if no tenderness at the “N” spot, then can
gradually return
 Reassess every 1-2 weeks, gradual return at 6 weeks if no
symptoms
 AFTER 6 weeks of protection, 6 weeks of PT for strength
and flexibility prior to return to run!
 Average return to play is 4-6 months
 Follow up radiography not helpful for return to activity
Sesamoid Stress Fracture
 Risk: Sudden start-stop sports
 Repetitive forced dorsiflexion
Sesamoid Stress Fracture
 Tx: NWB x 6 weeks with cast to tip of great toe to
prevent DF
 Failure: Surgery (excision or grafting)
Talus Stress Fracture
 Chronic pain after ankle sprain
 Location of fx: body near lateral process
 MRI or CT for best imaging
 Tx: 6-8 wks NWB in cast
 Failure to heal: Excision of lateral
process
Patella Stress Fracture
 Risk factors:
 cerebral palsy, hurdlers
 ACL reconstruction w/ BTB
 Tx if x-rays neg:
 Non-painful activity
 Tx if x-rays + or high-demand athlete
 K-wire fixation
Femoral Head Stress Fracture
 Tx: NWB
 Ortho referral; high rate of arthroplasty
Medial Malleolus Stress Fracture
 Seen in runners and jumpers
 Risk of non-union
 Tx if x-rays neg and MRI w/o fx line:
 SLWC or ankle brace; takes 4-5 MONTHS
 High-level athlete: surgery (FASTER RTP)
 Tx if x-rays + or non-union:
 Surgery
Orthopedic Consultation
 High Risk Fracture sites
 High Level Athlete/Laborer
 Failed conservative therapy
PREVENTION of STRESS FRACTURES
 Small incremental increases in training FITT
 Shock absorbing shoe/boot inserts
 Calcium 2000mg, Vit D 800 IU (27% decr.)
 Increased dairy products
 62% decreased risk SF for each cup of skim milk
 Modification of female recruit training:




Lower march speed
Softer surface
Individual step length/speed
Interval training instead of longer runs
 ??: OCPs (sig increase in bone mineral density, no
impact on stress fracture rate)
 NO: HCP selection of military recruits’ running shoes
based on foot morphology
 3 prospective studies by Knapik et al
QUESTIONS?

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